ESTRO 2024 - Abstract Book

S4745

Physics - Quality assurance and auditing

ESTRO 2024

account for radiobiology. Among these centers, one center (Center 4) scaled the dose to the spinal cord and the brainstem by a factor of 0.75 to account for repair since the first treatment. One center (Center 3) neither EQD2 corrected nor scaled the dose. We only present results for the oral cavity and the mandible structures in this abstract. These structures were selected due to overlap of the 50% isodose lines of both treatments (Figure 1 B). Including differences in local radiobiological dose corrections among the centers, we observed a range (maximum-minimum) in near-maximum dose (D 1% ) of 20.1 Gy for mandible (2A) and 18.4 Gy for oral cavity (2B). We found considerably lower dosimetric differences in the accumulated doses due to algorithm uncertainties alone, i.e. without radiobiological dose corrections, with D 1% range (maximum-minimum) of 9.5 Gy for mandible (2C) and 0.9 Gy for oral cavity (2D).

Conclusion: